Diamond, R v

Under Criminal Appeal Act 1968, s 23, fresh psychiatric evidence intended to support a new defence of diminished responsibility will usually be excluded where the defendant could have advanced that defence at trial. Admission is exceptional and depends on the interests of justice in the circumstances of the case.

Where a defendant was fit to plead, received clear advice, and tactically chose to deny the killing rather than advance diminished responsibility, the court will require a persuasive medical explanation showing that mental illness materially caused that choice. Retrospective psychiatric opinion carries less weight than contemporaneous assessments. A later diagnosis of mental illness does not itself provide a reasonable explanation for the failure to raise the defence at trial.

The appellant was convicted of murder at the Crown Court at Preston in 1999. Before trial, psychiatrists had identified a serious personality disorder and suspected a possible mental illness. The appellant refused a full assessment at Ashworth Hospital and instructed his lawyers to deny committing the killing. He was advised that diminished responsibility might be available.

After his conviction, the appellant was diagnosed with paranoid schizophrenia. A renewed application for permission to appeal was dismissed in 2003 after he would not pursue diminished responsibility. The Criminal Cases Review Commission later referred the conviction when he admitted the killing and psychiatric evidence supported both schizophrenia and diminished responsibility.

The central issue was whether fresh psychiatric evidence should be admitted under s 23 of the Criminal Appeal Act 1968, particularly whether mental illness had materially affected the appellant’s decision at trial not to advance diminished responsibility.

1. Appeal dismissed. The court declined to admit the fresh evidence relating to diminished responsibility under s 23 of the Criminal Appeal Act 1968. The murder conviction could not therefore be set aside.
2. The starting point was that a defendant must advance the whole available case at trial. In an appeal seeking to introduce a new defence of diminished responsibility, admission of fresh evidence is exceptional. The court must apply the ordinary statutory interests-of-justice discretion; there is no separate or higher evidential test merely because the evidence concerns diminished responsibility.
3. The court accepted that the appellant suffered from paranoid schizophrenia at the time of the killing and trial, although he was fit to plead. It nevertheless preferred Dr Snowden’s evidence on the decisive issue. The contemporaneous assessments were more reliable than a retrospective reconstruction made many years later.
4. The appellant had received competent and clear advice before trial to undergo assessment and consider diminished responsibility. His refusal was a tactical decision, principally motivated by the prospect of acquittal and his wish to defeat the prosecution. The court could not conclude that schizophrenia or lack of insight had played a material role in that decision.
5. Accordingly, there was no reasonable explanation for the failure to adduce the evidence at trial. It was neither necessary nor expedient in the interests of justice to admit Dr Collins’s later evidence on diminished responsibility.

The court also made observations for future cases. The established test for fitness to plead is narrow. A defendant may meet it while mental illness affects rational decision-making about a possible defence. If fit to plead, however, defence lawyers ordinarily must follow properly advised instructions; the prosecution must disclose mental-health material, and the judge’s role is very limited. The court considered that this potential gap in the law merited fuller examination if the occasion arose.

• Court of Appeal (Criminal Division): On a reference by the Criminal Cases Review Commission under s 9 of the Criminal Appeal Act 1995, the court dismissed the appeal and left the murder conviction standing.
• Court of Appeal (Criminal Division): In 2003, the renewed application for permission to appeal was dismissed after the appellant would not pursue diminished responsibility.
• Crown Court at Preston: In January 1999, the appellant was convicted of murder and sentenced to life imprisonment.